The following code generates "Specified argument was out of the range of valid values"
TaxonomySession session = new TaxonomySession(site);
TermStore termStore = session.TermStores["Managed Metadata Service"];
I have added the onlogged user and the user which the application pool uses to "Managed Metadata Service" and all other Services on "Manage service applications" by choosing them and click on Permissions on ribbon and check Full control, but still session.TermStores.Count is 0. I can go to the managed metadata service and see all groups and terms.
"Managed Metadata Service Proxy"
, but that wont help you until you get TermStore attached/running. How to do you access the Managed Metadata through Central Admin or through Site Settings? Are you sure that Web App is connected to the Managed Metadata?